I would thus think you don't want the errfile parameter -- unless it would be for catching these __del__ method that get triggered by input failing (for example your 'infile' parameter when called, allocated an object, which gets deallocated & throws an exception inside of its __del__ method).
If this is the purpose, then (back to 'how well documented the library is') -- it should be documented this is the purpose of the "errfile" parameter ;-)
[A secondary reason you might want to redirect "errfile" is that the passed in input or output file's, themselves do output to standard error ...]
I am happy to rename the args. What do you think about infile, outfile, and errfile?
FWIW, I did consider "in", "out", and "err", but "in" is a keyword, and I didn't think those quite captured the full meaning.
From: Amit Green <email@example.com>
Sent: Thursday, September 28, 2017 11:18:18 PM
To: Wren Turkal
Subject: Re: [Python-ideas] allow overriding files used for the input builtinBoth a function name & its keyword parameters need to be as understandable as possible when a user encounters them for the first time.Mostly though I would like to ask, please do not name keyword arguments with names like 'fin' & 'fout'. This is almost unreadable and make's code almost indecipherable to others the first time they see the function & its keyword arguments (First impressions are very important).Your example code, needs try/catch to match what the input with parameters does -- and yes, its way nicer to be able to use it the example you have shown than play games with try/catch (Personally I also refuse to ever change sys.stdin, or sys.stdout, as I consider that a bad coding style).I'm fine with the idea in general of extra keyword parameters to the input function.A few points:
On Fri, Sep 29, 2017 at 1:53 AM, Wren Turkal <firstname.lastname@example.org> wrote:
I have posted an idea for improvement with a PR of an implementation to https://bugs.python.org/iss
The basic idea is to add fin, fout, and ferr file object parameters and default to using what is used today when the args are not specified. I believe this would be useful to allow captures input and send output to specific files when using input. The input builtin has some logic to use readline if it's available. It would be nice to be able to use this same logic no matter what files are being used for input/output.
This is meant to turn code like the following:
orig_stdin = sys.stdin
orig_stdout = sys.stdout
with open('/dev/tty', 'r+') as f:
sys.stdin = f
sys.stdout = f
name = input('Name? ')
sys.stdin = orig_stdin
sys.stdout = orig_stdout
into something more like this:
with open('/dev/tty', 'r+') as f:
name = input('Name? ', fin=f, fout=f)
It's nice that it makes the assignment to a global variable to change the file used for input/output to no longer be needed.
I had this idea the other day, and I realized that it would be super easy to implement, so I went ahead the threw up a PR also.
Would love to see if anyone else is interested in this. I think it's pretty cool that the core logic really didn't need to be changed other than plumbing in the new args.
FWIW, this change introduces no regressions and adds a few more tests to test the new functionality. Honestly, I think this functionality could probably be used to simplify some of the other tests as well, but I wanted to gauge what folks thought of the change before going farther.
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